The present invention relates generally to operations performed within subterranean wells and, in an embodiment described herein, more particularly provides apparatus and methods for controlling fluid flow within a subterranean well.
In horizontal well open hole completions, fluid migration has typically been controlled by positioning a production tubing string within the horizontal wellbore intersecting a formation. An annulus formed between the wellbore and the tubing string is then packed with gravel. A longitudinally spaced apart series of sliding sleeve valves in the tubing string provides fluid communication with selected portions of the formation in relatively close proximity to an open valve, while somewhat restricting fluid communication with portions of the formation at greater distances from an open valve. In this manner, water and gas coning may be reduced in some portions of the formation by closing selected ones of the valves, while not affecting production from other portions of the formation.
Unfortunately, the above method has proved unsatisfactory, inconvenient and inefficient for a variety of reasons. First, the gravel pack in the annulus does not provide sufficient fluid restriction to significantly prevent fluid migration longitudinally through the wellbore. Thus, an open valve in the tubing string may produce a significant volume of fluid from a portion of the formation longitudinally remote from the valve. However, providing additional fluid restriction in the gravel pack in order to prevent fluid migration longitudinally therethrough would also deleteriously affect production of fluid from a portion of the formation opposite an open valve.
Second, it is difficult to achieve a uniform gravel pack in horizontal well completions. In many cases the gravel pack will be less dense and/or contain voids in the upper portion of the annulus. This situation results in a substantially unrestricted longitudinal flow path for migration of fluids in the wellbore.
Third, in those methods which utilize the spaced apart series of sliding sleeve valves, intervention into the well is typically required to open or close selected ones of the valves. Such intervention usually requires commissioning a slickline rig, wireline rig, coiled tubing rig, or other equipment, and is very time-consuming and expensive to perform. Furthermore, well conditions may prevent or hinder these operations.
Therefore, it would be advantageous to provide a method of controlling fluid flow within a subterranean well, which method does not rely on a gravel pack for restricting fluid flow longitudinally through the wellbore. Additionally, it would be advantageous to provide associated apparatus which permits an operator to produce or inject fluid from or into a selected portion of a formation intersected by the well. These methods and apparatus would be useful in open hole, as well as cased hole, completions.
It would also be advantageous to provide a method of controlling fluid flow within a well, which does not require intervention into the well for its performance. Such method would permit remote control of the operation, without the need to kill the well or pass equipment through the wellbore.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method is provided which utilizes selectively set and unset packers to control fluid flow within a subterranean well. The packers may be set or unset with a variety of power sources which may be installed along with the packers, provided at a remote location, or conveyed into the well when it is desired to set or unset selected ones of the packers. Associated apparatus is provided as well.
In broad terms, a method of controlling fluid flow within a subterranean well is provided which includes the step of providing a tubing string including a longitudinally spaced apart series of wellbore sealing devices. The sealing devices are selectively engaged with the wellbore to thereby restrict fluid flow between the tubing string and a corresponding selected portion of a formation intersected by the wellbore.
In one aspect of the present invention, the sealing devices are inflatable packers. The packers may be alternately inflated and deflated to prevent and permit, respectively, fluid flow longitudinally through the wellbore.
In another aspect of the present invention, flow control devices are alternated with the sealing devices along the tubing string to provide selective fluid communication between the tubing string and portions of the formation in relatively close proximity to the flow control devices. Thus, an open flow control device positioned between two sealing devices engaged with the wellbore provides unrestricted fluid communication between the tubing string and the portion of the formation longitudinally between the two sealing devices, but fluid flow from other portions of the formation is substantially restricted.
In yet another aspect of the present invention, the sealing devices and/or flow control devices may be actuated by intervening into the well, or by remote control. If intervention is desired, a fluid source, battery pack, shifting tool, pump, or other equipment may be conveyed into the well by slickline, wireline, coiled tubing, or other conveyance, and utilized to selectively adjust the flow control devices and selectively set or unset the sealing devices. If remote control is desired, the flow control devices and/or sealing devices may be actuated via a form of telemetry, such as mud pulse telemetry, radio waves, other electromagnetic waves, acoustic telemetry, etc. Additionally, the flow control devices and/or sealing devices may be actuated via hydraulic, electric and/or data transmission lines extending to a remote location, such as the earth""s surface or another location within the well.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed descriptions of representative embodiments of the invention hereinbelow and the accompanying drawings.